Collaborative Research: Fate and Consequences of Yakutat Terrane Subduction Beneath Eastern Alaska and the Wrangell Volcanic Field

合作研究：阿拉斯加东部和兰格尔火山场下雅库塔特地体俯冲的命运和后果

基本信息

批准号：
1460291
负责人：
Geoffrey Abers
金额：
$ 29.08万
依托单位：
Cornell University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2015
资助国家：
美国
起止时间：
2015-05-01 至 2021-04-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1460291&HistoricalAwards=false
关键词：
Collaborative Research Fate Consequences Yakutat

项目摘要

Non-Technical SummaryThe Wrangell Volcanic Field is one of the largest outpourings of volcanic rocks on the planet in the past 2.6 million years, but its relationship to processes of plate tectonics remains enigmatic. Locations of earthquakes underneath Alaska indicate that the Pacific plate is sliding beneath Alaska in a process of subduction. These earthquakes stop abruptly west of the Wrangell mountains, but somehow the plates continue to converge for several hundred kilometers eastward through the Wrangell region. Because of the close connections between subduction and mountain building, the south Alaska region provides an exceptional testing ground to test theories of how the mantle behaves when slabs end, and how convergence makes earthquakes in subduction zones. The centerpiece of this study is a temporary network of 37 broadband seismic stations deployed across southern Alaska to complement the EarthScope Transportable Array network along critical transects. It is providing data to tell whether or not subduction occurs under the Wrangells, and how the Alaska-Aleutian subduction zone ends. The research is being performed by a team with a well-established collaborative track record in advancing our understanding of subduction zones by deploying seismic arrays and integrating their results with other observations and models. Ongoing collaborations with petrologists and geodynamicists are helping spread the results to a broader geoscience audience. The project supports the training and professional development of two graduate students and provides excellent field-based opportunities to engage undergraduates in research. Outreach programs at the University of Alaska Fairbanks provide structured links to schools and science education centers in the region, reaching native populations with cutting-edge research. It supports an interdisciplinary collaboration with ample opportunity for the continued cross-disciplinary education among researchers and students. The Wrangell Volcanic Field represents a significant contributor to the total eruptive record in North America, and this study will provide critical framework for understanding this hazard as well.Technical DescriptionThe proposed research is aiding significantly in improving our understanding of the dynamics of subduction zones, the response of lithosphere to subduction of buoyant crust, mass conservation in slab contortions, and the drivers of arc volcanism. Results from the temporary deployment of 37 broadband seismic stations focus on determining slab surface and wedge geometry from receiver functions in addition to ambient noise tomography, velocity and attenuation imaging, tremor and seismicity studies, and measuring anisotropy from shear wave splitting. It addresses the following questions: 1) Where is the eastern end of the Alaska-Aleutian slab, and what is its configuration? Does it end as a tear, or is it continuously warped? 2) What is the relationship between Yakutat crust subduction, transtension, and volcanism in the Wrangell mountains? Does regular subduction drive Wrangell volcanism, or flow and high temperatures at a tear or edge? Does thick Yakutat terrane crust subduct continuously beneath the Wrangell mountains? 3) What is the flow around the end of the Aleutian slab and how much is it driven by subduction versus larger plate-scale flow? Results are being used to understand the fate of subducted material beneath Alaska and its role in driving volcanism&#8232; and tectonics.

非技术性总结wrangell火山场是过去260万年地球上火山岩最大的浇注之一，但其与板块构造过程的关系仍然是神秘的。阿拉斯加下方地震的位置表明，在俯冲过程中，太平洋板块在阿拉斯加的下方滑动。这些地震突然停在瑞吉尔山脉以西，但以某种方式，盘子继续汇聚在弗朗格尔地区以东数百公里。由于俯冲与山区建筑之间的紧密联系，南阿拉斯加地区提供了一个非凡的测试地面，以测试厚底时地幔的行为的理论，以及融合如何在俯冲带中的地震。这项研究的核心是由37个宽带地震站组成的临时网络，该网络部署在阿拉斯加南部，以补充沿关键样带的可运输阵列网络的补充。它提供了数据来判断俯冲是否发生在Wrangells下，以及阿拉斯加 - 亚利特俯冲区如何结束。这项研究是由一个团队进行的，具有完善的协作记录，以通过部署地震阵列并将其结果与其他观察结果和模型相结合，从而促进我们对俯冲区的理解。与岩石学家和地球动力学家的持续合作正在帮助将结果传播给更广泛的地球科学受众。该项目支持两名研究生的培训和专业发展，并提供了极好的基于现场的机会，以吸引本科生参与研究。阿拉斯加大学Fairbanks的外展计划提供了与该地区学校和科学教育中心的结构化联系，并通过尖端研究到达本地人口。它支持跨学科的合作，并为研究人员和学生之间的跨学科教育提供充足的机会。 Wrangell火山领域代表了北美爆发记录的重要贡献，这项研究还将为理解这种危害提供关键的框架。技术描述大大有助于提出的研究在提高我们对俯冲区域的动态方面的理解，岩石圈对Buoyant colloyant colloyant colloyant colloyant colloyant collant contrans in slab contortions and arc and arc anc anc anc anc anc anc droctrism and arctriver and arctriver and arctrest anc drocs anc drocs anc drocs and drovister。除环境噪声层析成像，速度和衰减成像，震颤和地震性研究外，还临时部署了37个宽带地震站的临时部署，重点是确定接收器功能的平板表面和楔形几何形状，并通过剪切波分开测量各向异性。它解决了以下问题：1）阿拉斯加 - 亚利特板的东端在哪里，其配置是什么？它会以眼泪而结束，还是不断扭曲？ 2）wangell山区的Yakutat lust俯冲，替身和火山之间有什么关系？常规的俯冲驱动器是否会驱动Wrangell火山，或者在眼泪或边缘流动和高温？厚的Yakutat地层外壳是否连续下方在Wrangell山下方？ 3）阿留申板末端的流量是多少，俯冲与较大的板尺度流动的驱动是多少？结果被用来了解阿拉斯加下方的俯冲材料的命运及其在驱动火山主义中的作用＆＃8232;和构造。